Method and device for sending pilot signal

ABSTRACT

Embodiments of the invention disclose a method and device for sending a pilot signal. The method includes: generating a sub-frame carrying user-specific pilot signals, wherein the sub-frame includes one or more resource blocks, the resource block includes a plurality of resource elements in a symbol-subcarrier plane, locations of the resource elements in the symbol-subcarrier plane are determined by an OFDM symbol and subcarrier, a first part of the user-specific pilots signal are carried by the resource elements of the initial one or more OFDM symbols in the resource block, and a second part of the user-specific pilot signals are carried by resource elements of other OFDM symbols in the resource block; and sending the sub-frame carrying the user-specific pilot signals. The methods and devices are capable of improving the precision of channel estimation.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2012/079731, filed on Aug. 6, 2012, which claims priority toChinese Patent Application No. 201110224400.7, filed on Aug. 5, 2011,both of which are hereby incorporated by reference in their entireties.

FIELD OF TECHNOLOGY

The present invention relates to wireless communication technologies, inparticular to a method and a device for sending a pilot signal.

BACKGROUND OF THE INVENTION

An increasing number of standards organizations use wirelesscommunication systems based on an orthogonal frequency divisionmultiplexing (Orthogonal Frequency Division Multiplexing, OFDM)technology because they can overcome inter-cell interference. In theOFDM technology, a whole frequency band is divided into a plurality ofsubcarriers, and user data are mapped onto the corresponding subcarriersfor transmission. The data of the communication system adopting the OFDMtechnology is carried by different OFDM symbols and subcarriers fortransmission, and a symbol-subcarrier plane is constructed by using theOFDM symbols and the subcarriers as two-dimensional coordinates.

In establishment of specifications of long term evolution advanced(LTE-A) of a next generation radio cellular mobile communication system,in order to meet the requirement of peak rate, a carrier aggregationtechnology is introduced. In the carrier aggregation technology, aplurality of branch carriers are aggregated and resources of a pluralityof branch carriers are scheduled for the use of a terminalsimultaneously. Spectra occupied by a plurality of branch carriers maybe continuous or discontinuous, the bandwidths of the branch carriersmay be same or different, and each branch carrier may be a carriercompatible with an LTE terminal or a carrier only supporting an LTE-Aterminal.

For a carrier which only supports LTE-A, the LTE terminal cannot performdata transmission or communication on the LTE-A carrier. In the priorart, in order to support the characteristics of an LTE-A system, besidesthat a certain carrier may be configured into the one which onlysupports the LTE-A terminal, a part of Physical Resource Block (PRB)resource may also be configured in a branch carrier into the one whichcannot be used by the LTE terminal.

Similar to other wireless communication systems, the wirelesscommunication system based on the OFDM technology needs to transmitpilot signals, and these pilot signals are distributed on atime-frequency plane according to certain pilot patterns. In the priorart, the specific pilot is designed on the basis of a backwardcompatible LTE sub-frame structure, namely, a sub-frame containscell-specific reference signals (Cell-specific reference signals, CRS),the first n OFDM symbols of each sub-frame are used for carrying aphysical downlink control channel (PDCCH), and a physical downlinkshared channel (PDSCH) for transmitting data starts from the (n+1)thOFDM symbol.

In a non-compatible carrier, because the PDCCH is not required to betransmitted, the PDSCH may start transmission from the first symbol, butthe specific pilot for channel estimation is placed on the last two OFDMsymbols in the first slot. A pattern of the specific pilot in a commoncyclic prefix (CP) sub-frame is taken as an example, and FIG. 1-FIG. 4show specific pilot patterns of common CP sub-frames of four differentantenna ports in LTE R10 version, wherein the specific pilot appearsfrom the 6th OFDM symbol, and PDSCH demodulation on the first 5 symbolsmay only be obtained by extrapolation by means of the channel estimationresult on the closest 6th symbol, and thus the precision of channelestimation is affected, and the data demodulation performance is furtheraffected.

SUMMARY OF THE INVENTION

The technical problem to be solved in the embodiments of the presentinvention is to provide a method and device for sending a pilot signalfor improving the precision of channel estimation.

In order to solve the above technical problem, provided in theembodiments of the present invention is a method for sending a pilotsignal. The method includes: generating a sub-frame which carriesuser-specific pilot signals, wherein the sub-frame includes one or moreresource blocks, the resource block includes a plurality of resourceelements in a symbol-subcarrier plane, locations of the resourceelements in the symbol-subcarrier plane are determined by OFDM symbolsand subcarriers, a first part of the user-specific pilot signals arecarried by resource elements of the initial one or more OFDM symbols inthe resource block, and a second part of the user-specific pilot signalsare carried by resource elements of the other OFDM symbols in theresource block; and sending the sub-frame carrying the user-specificpilot signals.

Correspondingly, also provided in the embodiment of the presentinvention is a pilot signal receiving method, including: receiving asub-frame carrying user-specific pilot signals, wherein the sub-frameincludes one or more resource blocks, the resource block includes aplurality of resource elements in a symbol-subcarrier plane, locationsof the resource elements in the symbol-subcarrier plane are determinedby OFDM symbols and subcarriers, a first part of the user-specific pilotsignals are carried by resource elements of the initial one or more OFDMsymbols in the resource block, and a second part of the user-specificpilot signals are carried by resource elements of the other OFDM symbolsin the resource block; and acquiring the user-specific pilot signalsaccording to the received sub-frame.

A transmitter in a wireless communication system includes: a generatingmodule, used for generating a sub-frame carrying user-specific pilotsignals, wherein the sub-frame includes one or more resource blocks, theresource block includes a plurality of resource elements in asymbol-subcarrier plane, locations of the resource elements in thesymbol-subcarrier plane are determined by OFDM symbols and subcarriers,a first part of the user-specific pilot signals are carried by resourceelements of the initial one or more OFDM symbols in the resource block,and a second part of the user-specific pilot signals are carried byresource elements of the other OFDM symbols in the resource block; and asending module, used for sending the sub-frame carrying theuser-specific pilot signals.

Moreover, provided is a receiver in a wireless communication system,including: a receiving module, used for receiving a sub-frame carryinguser-specific pilot signals, wherein the sub-frame includes one or moreresource blocks, the resource block includes a plurality of resourceelements in a symbol-subcarrier plane, locations of the resourceelements in the symbol-subcarrier plane are determined by OFDM symbolsand subcarriers, a first part of the user-specific pilot signals arecarried by resource elements of the initial one or more OFDM symbols inthe resource block, and a second part of the user-specific pilot signalsare carried by resource elements of the other OFDM symbols in theresource block; and an acquiring module, used for acquiring theuser-specific pilot signals according to the received sub-frame.

Moreover, provided is a wireless communication system, including atleast one aforementioned transmitter and at least one aforementionedreceiver.

The embodiments of the present invention have the following beneficialeffects: in the embodiments of the present invention, the user-specificpilot signals are added and carried by the resource elements of theinitial OFDM symbols of the resource block, the locations of the addedpilot signals do not occupy the locations of the existing pilot signals,and the added pilot is spaced from the neighboring pilot as much aspossible in the symbol-subcarrier plane, so that channel interpolationestimation is facilitated, and the precision of channel estimation isimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to illustrate the technical solution in the embodiments of thepresent invention or the prior art more clearly, brief description willbe made below to the drawings required in the embodiments of the presentinvention or the prior art, and apparently, the drawings described beloware some embodiments of the present invention only. Other drawings couldbe obtained from these drawings by those ordinary skilled in this artwithout creative efforts.

FIG. 1 shows a specific pilot pattern of a common CP sub-frame of anantenna port 7 in an existing LTE R10 version;

FIG. 2 shows a specific pilot pattern of a common CP sub-frame of anantenna port 8 in an existing LTE R10 version;

FIG. 3 shows a specific pilot pattern of a common CP sub-frame of anantenna port 9 in an existing LTE R10 version;

FIG. 4 shows a specific pilot pattern of a common CP sub-frame of anantenna port 10 in an existing LTE R10 version;

FIG. 5 is a specific flow schematic view of a method for sending a pilotsignal in an embodiment of the present invention;

FIG. 6 shows a pilot pattern of a common CP sub-frame at antenna ports 7and 8 in an embodiment of the present invention;

FIG. 7 shows a pilot pattern of a sub-frame with a common CP structureat antenna ports 9 and 10 in an embodiment of the present invention;

FIG. 8 is a schematic view of orthogonal code mapping of a common CPsub-frame in an embodiment of the present invention;

FIG. 9 shows a pilot pattern of a sub-frame with an extended CPstructure at antenna ports 7 and 8 in an embodiment of the presentinvention;

FIG. 10 shows a schematic view of orthogonal code mapping of an extendedCP sub-frame in an embodiment of the present invention;

FIG. 11 shows another pilot pattern of a sub-frame with an extended CPstructure at antenna ports 7 and 8 in an embodiment of the presentinvention;

FIG. 12 is another schematic view of orthogonal code mapping of anextended CP sub-frame in an embodiment of the present invention;

FIG. 13 shows a third pilot pattern of a sub-frame with an extended CPstructure at antenna ports 7 and 8 in an embodiment of the presentinvention;

FIG. 14 shows a third fourth pilot pattern of a sub-frame with anextended CP structure at antenna ports 7 and 8 in an embodiment of thepresent invention;

FIG. 15 shows another pilot pattern of a sub-frame with a common CPstructure at antenna ports 7 and 8 in an embodiment of the presentinvention;

FIG. 16 shows another pilot patterns of a sub-frame with an extended CPstructure at antenna ports 9 and 10 in an embodiment of the presentinvention;

FIG. 17 shows a fifth pilot pattern of a sub-frame with an extended CPstructure at antenna ports 7 and 8 in an embodiment of the presentinvention;

FIG. 18 is a specific flow schematic view of pilot signal receivingmethod in an embodiment of the present invention; and

FIG. 19 is a specific composition schematic view of a wirelesscommunication system in an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The technical solution in the embodiments of the present invention willbe described clearly and fully below in conjunction with the drawings inthe embodiments of the present invention, and apparently, theembodiments described are only part of embodiments of the presentinvention, not all of them. Based on the embodiments of the presentinvention, all the other embodiments acquired by ordinary skilled inthis art without creative efforts shall fall within the protection scopeof the present invention.

Pilot signals are carried by resource elements of initial OFDM symbolsof a resource block of a sub-frame in the embodiments of the presentinvention, for example, pilot resources may also be carried at locationsof the initial OFDM symbols of the resource block on the basis of thepilot patterns listed in FIG. 1 to FIG. 4, so on the one hand, locationsof the existing pilot resources are not required to be modified, and onthe other hand, pilot resources carried at the locations are favorablefor improving the precision of channel estimation.

FIG. 5 shows a specific flow schematic view of a method for sending apilot signal in the embodiment of the present invention. The method inthe embodiment of the present invention may be applied to non-compatiblecarriers; and for compatible carriers, sub-frames of an LTE sub-framestructure based on backward compatibility contains cell-specificreference signals (CRS), if the first n OFDM symbols of each sub-frameare used for carrying a physical downlink control channel (PhysicalDownlink Control Channel, PDCCH), a physical downlink shared channel(Physical Downlink Shared Channel, PDSCH) for transmitting data startsfrom the (n+1)th OFDM symbol.

The pilot signal method in the embodiment of the present inventionincludes the following steps.

501, a sub-frame carrying user specific pilot signals is generated,wherein the sub-frame includes one or more resource blocks, the resourceblock includes a plurality of resource elements in a symbol-subcarrierplane, locations of the resource elements in the symbol-subcarrier planeare determined by OFDM symbols and subcarriers, a first part of theuser-specific pilot signals are carried by resource elements of theinitial one or more OFDM symbols in the resource block, and a secondpart of the user-specific pilot signals are carried by resource elementsof other OFDM symbols in the resource block.

A resource block in a sub-frame sent by antenna ports 7-8, as shown inFIG. 6, has 14*12 resource blocks. In FIG. 6, transverse coordinates areOFDM symbols, and longitudinal coordinates are subcarriers.

It is determined in the embodiment of the present invention that a partof the user-specific pilot signals are carried by the resource elementsof the initial one or more OFDM symbols in the resource block and otherpart of the user-specific pilot signals are carried by the resourceelements of the other OFDM symbols in the resource block, and whenspecific pilot patterns (the pilot patterns denote patterns forreflecting locations of resource elements for carrying pilot in aresource block) are determined accordingly, reference may be made to theexisting pilot patterns, and the carried pilot is added only at resourceelements of the initial OFDM symbols on the existing pilot patterns. Inthis way, the existing pilot patterns are modified little as in eachembodiment of FIG. 6 to FIG. 14. Of course, the pilot pattern in theembodiment of the present invention is not necessarily to be so, forexample, in the embodiment of FIG. 15, besides that the pilot pattern iscarried by the resource elements of the initial OFDM symbols of theresource block, the pilot pattern is only carried by the resourceelements of the final OFDM symbol of the resource block.

When a part of the user-specific pilot signals are carried by theresource elements of the initial more than one OFDM symbols in theresource block, resource elements of the first OFDM symbol, second OFDMsymbol or two continuous OFDM symbols starting from the initial OFDMsymbols in each sub-frame resource block may be selected. Of course,according to the actual requirement, resource elements of the initialmore than two OFDM symbols may also be selected for carrying the firstpart of the user-specific pilot signals.

As for the coordinates of subcarriers of the resource elements forcarrying the pilot, it is possible that an interval of subcarriers ofthe resource elements for carrying the first part of the user-specificpilot signals may be the same as an interval of subcarriers of theresource elements for carrying the second part of the user-specificpilot signals. Even, it is possible that the subcarriers of the resourceelements for carrying the first part of the user-specific pilot signalsmay be the same as the subcarriers of the resource elements for carryingthe second part of the user-specific pilot signals.

FIG. 6 and FIG. 7 show the condition that the an interval of subcarriersof the resource elements for carrying the first part of theuser-specific pilot signals are same and the subcarriers are also same,wherein the first part of the user-specific pilot signals meansuser-specific pilot signals in the first column and the second column(namely, the first two columns) of the resource block, and the secondpart of the user-specific pilot signals means user-specific pilotsignals in the middle two columns and the last two columns; in FIG. 9,the subcarriers of the resource elements for carrying the first part ofthe user-specific pilot signals (the first part of the user-specificpilot signals means user-specific pilot signals in the first two columnsof the resource block) and the second part of the user-specific pilotsignals (the second part of the user-specific pilot signals meansuse-specific pilot signals in the middle two columns) are different, butthe an interval of the subcarriers are same. In this way, in theobtained pilot patterns, locations for carrying pilot in the wholesub-frame may be more uniform, so that the precision of channelestimation is furthest improved, and the performance of datademodulation is improved.

502, a sub-frame carrying the user-specific pilot signals is sent.

In the embodiment of the present invention, when sub-frames carrying thepilot signals are sent at the different antenna ports, the pilotpatterns thereof are probably same, for example, the pilot patterns ofthe antenna port 7 and the antenna port 8 illustrated in FIG. 6 aresame. In order to enable a receiving end to distinguish pilots ofdifferent antennas, when the pilot signals are sent at a sending end,the user-specific pilot signals sent at different antenna ports aremapped by using different orthogonal codes in the sub-frames carryingthe user-specific pilot signals and sent by different antenna ports, sothat the receiving end can distinguish the pilots of different antennasat the same time-frequency location. In some specific embodiments of thepresent invention, distinguishing can be realized through differentpilot patterns of different antennas, and the orthogonal codes are notrequired.

Namely, when the sub-frames carrying the user-specific pilot signals aresent at different antenna ports, OFDM symbols or/and subcarriers of theresource elements for carrying the user-specific pilot signals in thesub-frame sent at the first antenna port are different from OFDM symbolsor/and subcarriers of the resource elements for carrying theuser-specific pilot signals in the sub-frame sent at the second antennaport; or,

OFDM symbols or/and subcarriers of the resource elements for carryingthe first part of the user-specific pilot signals in the sub-frame sentat the first antenna port are different from the OFDM symbols or/and thesubcarriers of the resource elements for carrying the first part of theuser-specific pilot signals in the sub-frame sent at the second antennaport, and OFDM symbols or/and subcarriers of the resource elements forcarrying the second part of the user-specific pilot signals in thesub-frame sent at the first antenna port are the same as OFDM symbolsor/and subcarriers of the resource elements for carrying the second partof the user-specific pilot signals in the sub-frame sent at the secondantenna port.

For example, one of the antenna port 7 and the antenna port 8 may carrypilot by using resource element of the initial first OFDM symbol of thesub-frame resource block, and the other one may carry pilot by usingresource element of the initial second OFDM symbol of the sub-frameresource block. Or, the initial OFDM symbols of the resource elementsfor carrying pilot at the two antennas are same, but the subcarriers ofthe resource elements are different.

In the embodiment of the present invention, when the resource elementsfor carrying pilot are determined, the resource elements may be definedaccording to the following formulas, and the resource elements forcarrying pilot, determined according to these formulas, may also includethe resource elements with initial OFDM symbols.

For example, for a resource block sent at a antenna port p and having anindex n_(PRB), (k, l) is coordinate of a resource element in theresource block with the index n_(PRB) in the symbol-subcarrier plane,wherein k denotes an index of a subcarrier, l denotes an index of anOFDM symbol, and a pilot sequence r^(( m)) in the resource block iscarried by modulation symbols a_(k,l) ^((p)) of the resource elements(k, l);

9

when the sub-frame is a common CP sub-frame, the first part of theuser-specific pilot signals carried by the resource elements of theinitial one or more OFDM symbols in the resource block are denoted as:

a _(k,l) ^((p)) =w _(p)(l′)·r(3·l′·N _(RB) ^(max,DL)+3·n _(PRB) +m′)

wherein,

${w_{p}(i)} = \left\{ {{\begin{matrix}{{\overset{\_}{w}}_{p}(i)} & {{\left( {m^{\prime} + n_{PRB}} \right){{mod}2}} = 0} \\{{\overset{\_}{w}}_{p}\left( {3 - i} \right)} & {{\left( {m^{\prime} + n_{PRB}} \right){mod}\; 2} = 1}\end{matrix}k} = {{{5m^{\prime}} + {N_{sc}^{RB}n_{PRB}} + {k^{\prime}k^{\prime}}} = \left\{ {{\begin{matrix}1 & {p \in \left\{ {7,8,11,13} \right\}} \\0 & {p \in \left\{ {9,10,12,14} \right\}}\end{matrix}l} = {l^{\prime}{{mod}2}}} \right.}} \right.$

l′=4,5 if n_(s)mod2=0, and not belong to a special sub-frame of TDDconfiguration 1, 2, 6 or 7,

m′=0,1,2

when the sub-frame is an extended CP sub-frame, the resource elementsfor carrying the first part of the user-specific pilot signals may bedenoted as:

a _(k,l) ^((p)) =2 _(p)(l′)·r(4·l′·N _(RB) ^(max,DL)+4·n _(PRB) +m′)

wherein

${w_{p}(i)} = \left\{ {{\begin{matrix}{{\overset{\_}{w}}_{p}(i)} & {{m^{\prime}{{mod}2}} = 0} \\{{\overset{\_}{w}}_{p}\left( {1 - i} \right)} & {{m^{\prime}{{mod}2}} = 1}\end{matrix}k} = {{3m^{\prime}} + {N_{sc}^{RB}n_{PRB}} + k^{\prime}}} \right.$

k′=2 if n_(s)mod2=0 and p ∈ {7,8}

l=l′mod2

l′=0,1 if n_(s)mod2=0

m′=0,1,2,3

the sequence w _(p)(i) is an orthogonal sequence for distinguishingdifferent antenna ports.

According to the aforementioned described method, described are severalpilot patterns in different embodiments of the present inventionrespectively.

FIG. 6 to FIG. 7 show the pilot patterns (the pilot patterns of theantenna ports with smaller sequence numbers on the left in the figures)adopted when a sub-frame with a common CP structure provided by theembodiment of the present invention send signals at the antenna ports7-10. In this embodiment, the resource elements for carrying the firstpart of the pilot have the same subcarriers (namely, the coordinates ofthe subcarriers are consistent) as the resource elements for carryingthe second part of the pilot at the same antenna port. In theembodiments shown in FIG. 6 to FIG. 7, the OFDM symbols of the resourceelements for carrying the first part of the user-specific pilot signalsare the first and second OFDM symbols of the resource block.

Mapping is performed on the pilot patterns by using orthogonal codes inthe embodiment of the present invention to distinguish user-specificpilot signals of different antenna ports on the same time-frequencyresource, for example, the mapped resource block as shown in FIG. 8 isobtained, and a, b, c and d in the figure are defined as formula 1.

$\begin{matrix}{W_{4} = {\begin{pmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\1 & 1 & {- 1} & {- 1} \\1 & {- 1} & {- 1} & 1\end{pmatrix} = \begin{pmatrix}a & b & c & d\end{pmatrix}}} & {{Formula}\mspace{14mu} 1}\end{matrix}$

This code division design may keep the two-dimensional orthogonalproperty of the specific pilot on a time-frequency domain. The specificsequence on each antenna port is shown as the first two digits in thesecond column of Table 1.

TABLE 1 antenna port sequence number^(p) [ w _(p)(4) w _(p)(5) w _(p)(0)w _(p)(1) w _(p)(2) w _(p)(3)] 7 [+1 +1 +1 +1 +1 +1] 8 [+1 −1 +1 −1 +1−1] 9 [+1 +1 +1 +1 +1 +1] 10 [+1 −1 +1 −1 +1 −1] 11 [−1 −1 +1 +1 −1 −1]12 [+1 +1 −1 −1 +1 +1] 13 [−1 +1 +1 −1 −1 +1] 14 [+1 −1 −1 +1 +1 −1]

In this example, the pilot pattern may be defined according to thefollowing formula. Namely, for a resource block sent at a antenna port pand having an index n_(PRB), (k, l) is coordinate of a resource elementin the resource block with the index n_(PRB) in the symbol-subcarrierplane, wherein k denotes an index of a subcarrier, l denotes an index ofan OFDM symbol, and the pilot sequence r(m) carried by the resourceblock is carried by modulation symbols a_(k,l) ^((p)) of the resourceelements (k, l).

The sub-frame is a common CP sub-frame, and the resource elements forcarrying the first part of the user-specific pilot signals may bedenoted as:

a _(k,l) ^((p)) =w _(p)(l′)·r(3·l′·N _(RB) ^(max,DL)+3·n _(PRB) +m′)

wherein m=3·l′·N_(RB) ^(max,DL)+3·n_(PRB)+m′,

${w_{p}(i)} = \left\{ {{\begin{matrix}{{\overset{\_}{w}}_{p}(i)} & {{\left( {m^{\prime} + n_{PRB}} \right){{mod}2}} = 0} \\{{\overset{\_}{w}}_{p}\left( {3 - i} \right)} & {{\left( {m^{\prime} + n_{PRB}} \right){mod}\; 2} = 1}\end{matrix}k} = {{{5m^{\prime}} + {N_{sc}^{RB}n_{PRB}} + {k^{\prime}k^{\prime}}} = \left\{ {{\begin{matrix}1 & {p \in \left\{ {7,8,11,13} \right\}} \\0 & {p \in \left\{ {9,10,12,14} \right\}}\end{matrix}l} = {l^{\prime}{{mod}2}}} \right.}} \right.$

l′=4,5 if n_(s)mod 2=0, and not belong to a special sub-frame of TDDconfiguration 1, 2, 6 or 7,

m′=0,1,2.

The sequence w _(p)(i) is an orthogonal sequence for distinguishingdifferent antenna ports. If the orthogonal sequence in Table 1 isadopted, the values of i (namely, l′) in this example are 0, 1, 2, 3, 4and 5 respectively.

FIG. 9 shows the pilot patterns (the pilot patterns of the antenna portswith smaller sequence numbers on the left in the figure) of a sub-framewith an extended CP structure at the antenna ports 7 and 8. In thisembodiment, the subcarriers of the resource elements for carrying thefirst part of the user-specific pilot signals are different fromsubcarriers of the resource elements for carrying the second part of theuser-specific pilot signals (namely, the second part of theuser-specific pilot signals are only the pilot in the resource elementsof the middle column, and the subcarriers of the resource elements forcarrying the first part of the user-specific pilot signals are differentfrom those of the closest column thereof) and are staggered at aresource element interval, and the OFDM symbols of the resource elementsfor carrying the first part of the user-specific pilot signals are thefirst and second OFDM symbols of the resource block.

The specific pilots of different antenna ports on the sametime-frequency resource are distinguished by using orthogonal codes toobtain mapped resource blocks as shown in FIG. 10, and a and b in thefigure are defined as the following formula.

$W_{2} = {\begin{pmatrix}1 & 1 \\{- 1} & 1\end{pmatrix} = \begin{pmatrix}a & b\end{pmatrix}}$

The sub-frame in this example is an extended CP sub-frame, and theresource elements for carrying the first part of the user-specific pilotsignals are denoted as (the meaning of each element in the formula isconsistent with that in the aforementioned embodiments):

a _(k,l) ^((p)) =w _(p)(l′)·r(4·l′·N _(RB) ^(max,DL)+4·n _(PRB) +m′)

Wherein

${w_{p}(i)} = \left\{ {{\begin{matrix}{{\overset{\_}{w}}_{p}(i)} & {{m^{\prime}{{mod}2}} = 0} \\{{\overset{\_}{w}}_{p}\left( {1 - i} \right)} & {{m^{\prime}{{mod}2}} = 1}\end{matrix}k} = {{3m^{\prime}} + {N_{sc}^{RB}n_{PRB}} + k^{\prime}}} \right.$

k′=2 if n_(s)mod2=0 and p ∈ {7,8}

l=l′mod2

l′=0,1 if n_(s)mod2=0

m′=0,1,2,3

The sequence w _(p)(i) is an orthogonal sequence for distinguishingdifferent antenna ports. For example, the orthogonal sequence as shownin Table 2 is adopted, at this moment, the value of i may be 0 or 1.

TABLE 2 antenna port sequence number^(p) [ w _(p)(0) w _(p)(1)] 7 [+1+1] 8 [−1 +1]

FIG. 11 shows the pilot patterns (the pilot patterns of the antennaports with smaller sequence numbers on the left in the figure) of asub-frame with an extended CP structure at the antenna ports 7 and 8. Inthis embodiment, the subcarriers of the resource elements for carryingthe first part of the user-specific pilot signals are the same as thesubcarriers of the resource elements for carrying the second part of theuser-specific pilot signals (namely, the second part of theuser-specific pilot signals are only the pilot in the resource elementsof the middle column, and the subcarriers of the resource elements forcarrying the first part of the user-specific pilot signals are only thesame as those of the closest column thereof), and the OFDM symbols ofthe resource elements for carrying the first part of the user-specificpilot signals are the first and second OFDM symbols of the resourceblock. The specific pilots of different antenna ports on the sametime-frequency resource are distinguished by using orthogonal codes toobtain mapped resource blocks as shown in FIG. 12, and a and b in thefigure are defined as formula 1.

FIG. 13 shows the third pilot patterns of a sub-frame with an extendedCP structure, and shows the specific pilot design patterns (the pilotpatterns of the antenna ports with smaller sequence numbers on the leftin the figure) on the antenna ports 7 and 8. In this embodiment, theOFDM symbols of the resource elements for carrying the first part of theuser-specific pilot signals are the first OFDM symbol or second OFDMsymbol, namely, the pilots on different antenna ports adopt a timedivision multiplexing (Time Division Multiplexing, TDM) mode. So, inthis example, orthogonal codes for mapping are not required to bedesigned. Of course, in this example, the OFDM symbols of the resourceelements for carrying the first part of the user-specific pilot signalson the antenna port 7 and carrying the first part of the user-specificpilot signals on the antenna port 8 may be interchanged.

FIG. 14 shows the fourth pilot pattern of a sub-frame with an extendedCP structure, and shows the specific pilot design patterns (in thefigure, the antenna ports 7 and 8 only have the difference thatlocations of the resource elements for carrying the first part of theuser-specific pilot signals are different, and different subscripts of Rrepresent the locations of the resource elements for carrying the firstpart of the user-specific pilot signals in different antenna ports) onthe antenna ports 7 and 8. In this embodiment, the OFDM symbol of theresource elements for carrying the first part of the user-specific pilotsignals are the first OFDM symbol, but the subcarriers of the resourceelements for carrying the first part of the user-specific pilot signalsare different, namely, the pilots on different antenna ports adopt atime division multiplexing (TDM) mode. So, in this example, orthogonalcodes are not required to be designed for mapping. Of course, in thisexample, the locations of the subcarriers of the resource elements forcarrying the first part of the user-specific pilot signals on theantenna port 7 and carrying the first part of the user-specific pilotsignals on the antenna port 8 may be interchanged.

FIG. 15 to FIG. 16 show another pilot pattern of a sub-frame with acommon CP structure, and show specific pilot design patterns (the pilotpatterns of the antenna ports 7 and 8 are same in the figures) on theantenna ports 7-10. In this embodiment, the OFDM symbols of the resourceelements for carrying the first part of the user-specific pilot signalsare the first and second OFDM symbols, and the subcarriers of theresource elements for carrying the first part of the user-specific pilotsignals are the same as the subcarriers of the resource elements forcarrying the second part of the user-specific pilot signals.

FIG. 17 shows the fifth pilot patterns of a sub-frame with an extendedCP structure, and shows specific pilot design patterns (the pilotpatterns of the antenna ports 7 and 8 are same in the figure) on theantenna ports 7 and 8. In this embodiment, the OFDM symbols of theresource elements for carrying the first part of the user-specific pilotsignals are the first and second OFDM symbols, the subcarriers of theresource elements for carrying the first part of the user-specific pilotsignals are different from subcarriers of the resource elements forcarrying the second part of the user-specific pilot signals, but theintervals thereof are same.

Based on each embodiment described above, it shall be easily understoodthat, more different pilot patterns may also be designed according tothe method provided by the present invention, and these pilot patternsshould fall within the scope protected by the embodiments of the presentinvention and are not repeated one by one here.

Correspondingly, also provided in the embodiments of the presentinvention is a pilot signal receiving method, as shown in FIG. 18, andthe method includes the following steps.

1801, a sub-frame carrying user-specific pilot signals is received,wherein the sub-frame includes one or more resource blocks, the resourceblock includes a plurality of resource elements in a symbol-subcarrierplane, locations of the resource elements in the symbol-subcarrier planeare determined by OFDM symbols and subcarriers, a first part ofuser-specific pilot signals are carried by the resource elements of theinitial one or more OFDM symbols in the resource block, and a secondpart of the user-specific pilot signals are carried by the resourceelements of the other OFDM symbols in the resource block; and

1802, the user-specific pilot signals are acquired according to thereceived sub-frame.

The locations of the resource elements for carrying the user-specificpilot signals in this embodiment are similar to those of theaforementioned embodiments. For example, the resource elements of theinitial one or more OFDM symbols in the resource block include theresource elements of the initial first OFDM symbol, second OFDM symbolor two continuous OFDM symbols in the resource block. An interval ofsubcarrier of the resource elements for carrying the first part of theuser-specific pilot signals may be the same as an interval of subcarrierof the resource elements for carrying the second part of theuser-specific pilot signals. Even, the subcarriers of the resourceelements for carrying the first part of the user-specific pilot signalsare also the same as subcarriers of the resource elements for carryingthe second part of the user-specific pilot signals.

On the other hand, the receiving the sub-frame carrying theuser-specific pilot signals may include:

receiving the sub-frame carrying the user-specific pilot signals, whichis sent at a first antenna port and a second antenna port;

wherein OFDM symbols or/and subcarriers of the resource elements forcarrying the user-specific pilot signals in the sub-frame sent at thefirst antenna port are different from OFDM symbols or/and subcarriers ofthe resource elements for carrying the user-specific pilot signals inthe sub-frame sent at the second antenna port; or,

OFDM symbols or/and subcarriers of the resource elements for carryingthe first part of the user-specific pilot signals in the sub-frame sentat the first antenna port are different from OFDM symbols or/andsubcarriers of the resource elements for carrying the first part of theuser-specific pilot signals in the sub-frame sent at the second antennaport, and OFDM symbols or/and subcarriers of the resource elements forcarrying the second part of the user-specific pilot signals in thesub-frame sent at the first antenna port are the same as OFDM symbolsor/and subcarriers of the resource elements for carrying the second partof the user-specific pilot signals in the sub-frame sent at the secondantenna port.

Or the step includes: receiving the sub-frame carrying the user-specificpilot signals, which is sent at the first antenna port and the secondantenna port, wherein locations of the resource elements for carryingthe user-specific pilot signals in the sub-frame sent at the firstantenna port are the same as locations of the resource elements forcarrying the user-specific pilot signals in the sub-frame sent at thesecond antenna port; and the user-specific pilot signals sent at thefirst antenna port and the second antenna port are mapped by usingdifferent orthogonal codes.

The ordinary skilled in the art should understand that this embodimentmay be used for receiving the user-specific pilot patterns shown in FIG.6 to FIG. 17, so repeated descriptions one by one are omitted here.

As shown in FIG. 19, a wireless communication system in the embodimentsof the present invention may include a transmitter 1 and a receiver 2.The transmitter 1 includes: a generating module 10, used for generatinga sub-frame carrying user-specific pilot signals, wherein the sub-frameincludes one or more resource blocks, the resource block includes aplurality of resource elements in a symbol-subcarrier plane, locationsof the resource elements in the symbol-subcarrier plane are determinedby OFDM symbols and subcarriers, a first part of the user-specific pilotsignals are carried by resource elements of the initial one or more OFDMsymbols in the resource block, and a second part of the user-specificpilot signals are carried by the resource elements of other OFDM symbolsin the resource block; and a sending module 12, used for sending thesub-frame carrying the user-specific pilot signals.

In the sub-frame generated by the generating module, an interval ofsubcarrier of the resource elements for carrying the first part of theuser-specific pilot signals are the same as those of the resourceelements for carrying the second part of the user-specific pilotsignals. Or, the subcarriers of the resource elements for carrying thefirst part of the user-specific pilot signals are the same assubcarriers of the resource elements for carrying the second part of theuser-specific pilot signals.

Meanwhile, the sending module 12 may also include a first antenna port120 and a second antenna port 122; in the sub-frame generated by thegenerating module 10, OFDM symbols or/and subcarriers of the resourceelements for carrying the user-specific pilot signals in the sub-framesent at the first antenna port are different from OFDM symbols or/andsubcarriers of the resource elements for carrying the user-specificpilot signals in the sub-frame sent at the second antenna port; or,

OFDM symbols or/and subcarriers of the resource elements for carryingthe first part of the user-specific pilot signals in the sub-frame sentat the first antenna port are different from OFDM symbols or/andsubcarriers of the resource elements for carrying the first part of theuser-specific pilot signals in the sub-frame sent at the second antennaport, and OFDM symbols or/and subcarriers of the resource elements forcarrying the second part of the user-specific pilot signals in thesub-frame sent at the first antenna port are the same as OFDM symbolsor/and subcarriers of the resource elements for carrying the second partof the user-specific pilot signals in the sub-frame sent at the secondantenna port.

Or, the first antenna port and the second antenna port are used forsending the sub-frame carrying the user-specific pilot signals;

wherein locations of the resource elements for carrying theuser-specific pilot signals in the sub-frame sent at the first antennaport are the same as locations of the resource elements for carrying theuser-specific pilot signals in the sub-frame sent at the second antennaport; and the user-specific pilot signals sent at the first antenna portand the second antenna port are mapped by using different orthogonalcodes.

The receiver 2 includes: a receiving module 20, used for receiving asub-frame carrying user-specific pilot signals, wherein the sub-frameincludes one or more resource blocks, the resource block includes aplurality of resource elements in a symbol-subcarrier plane, locationsof the resource elements in the symbol-subcarrier plane are determinedby OFDM symbols and subcarriers, a first part of the user-specific pilotsignals are carried by the resource elements of the initial one or moreOFDM symbols in the resource block, and a second part of theuser-specific pilot signals are carried by the resource elements of theother OFDM symbols in the resource block; and

an acquiring module 22, used for acquiring the user-specific pilotsignals according to the received sub-frame.

In the sub-frame received by the receiving module 20, an interval ofsubcarriers of the resource elements for carrying the first part of theuser-specific pilot signals are the same as an interval of subcarriersof the resource elements for carrying the second part of theuser-specific pilot signals.

Or, the receiving module 20 is further used for receiving the sub-framecarrying the user-specific pilot signals, which is sent at a firstantenna port and a second antenna port,

wherein OFDM symbols or/and subcarriers of the resource elements forcarrying the user-specific pilot signals in the sub-frame sent at thefirst antenna port are different from OFDM symbols or/and subcarriers ofthe resource elements for carrying the user-specific pilot signals inthe sub-frame sent at the second antenna port; or,

the OFDM symbols or/and the subcarriers of the resource elements forcarrying the first part of the user-specific pilot signals in thesub-frame sent at the first antenna port are different from OFDM symbolsor/and subcarriers of the resource elements for carrying the first partof the user-specific pilot signals in the sub-frame sent at the secondantenna port, and OFDM symbols or/and subcarriers of the resourceelements for carrying the second part of the user-specific pilot signalsin the sub-frame sent at the first antenna port are the same as OFDMsymbols or/and subcarriers of the resource elements for carrying thesecond part of the user-specific pilot signals in the sub-frame sent atthe second antenna port.

Or, locations of the resource elements for carrying the user-specificpilot signals in the sub-frame sent at the first antenna port are thesame as locations of the resource elements for carrying theuser-specific pilot signals in the sub-frame sent at the second antennaport; and the user-specific pilot signals sent at the first antenna portand the user-specific pilot signals sent at the second antenna port aremapped by using different orthogonal codes.

Those ordinary skilled in the art should understand that, thetransmitter 1 may be used for sending the user-specific pilot patternsshown in FIG. 6 to FIG. 17, the receiver 2 may be used for receiving theuser-specific pilot patterns shown in FIG. 6 to FIG. 17, for simplicity,repeated description is omitted here.

In the embodiments of the present invention, the user-specific pilotsignals are added and carried by the resource elements of the initialOFDM symbols of the resource block, the locations of the new added pilotsignals do not occupy the locations of the existing pilot signals, andthe new added pilot is spaced from the neighboring pilot as much aspossible in the symbol-subcarrier plane, so that channel interpolationestimation is facilitated, and the precision of channel estimation isimproved.

Those ordinary skilled in the art should understand that all of or partof the flows in the methods of the aforementioned embodiments may becompleted by instructing related hardware through computer programs, theprograms may be stored in a computer-readable storage medium, and whenthe programs are executed, the flows of the embodiments of eachaforementioned method may be included, wherein the storage medium may bedisk, optical disk, read-only memory (ROM) or random access memory (RAM)and the like.

The description above is only the preferred embodiments of the presentinvention, but not to limit the protection scope of the presentinvention, so equivalent variations made according to the claims of thepresent invention are still encompassed in the scope of the presentinvention.

What is claimed is:
 1. A method for sending a pilot signal, comprising:generating a resource block carrying user-specific pilot signals; andsending the user-specific pilot signals; wherein the resource blockcomprises a plurality of resource elements in a symbol-subcarrier plane,wherein locations of the resource elements in the symbol-subcarrierplane are determined by Orthogonal Frequency Division Multiplexing(OFDM) symbols and subcarriers, wherein a first part of theuser-specific pilot signals are carried by resource elements occupyingone or more of the group consisting of: an initial OFDM symbol, a secondOFDM symbol, and a third OFDM symbol horizontally listed in the resourceblock, and wherein the initial OFDM symbol, the second OFDM symbol, andthe third OFDM symbol are horizontally listed in the resource block. 2.The method of claim 1, wherein a second part of the user-specific pilotsignals are carried by resource elements occupying OFDM symbolshorizontally listed in the resource block other than the groupconsisting of: the initial OFDM symbol, the second OFDM symbol, and thethird OFDM symbol, and wherein an interval of subcarriers occupied bythe resource elements for carrying the first part of the user-specificpilot signals is the same as interval of subcarriers occupied by theresource elements for carrying the second part of the user-specificpilot signals.
 3. The method of claim 1, wherein a second part of theuser-specific pilot signals are carried by resource elements occupyingOFDM symbols horizontally listed in the resource block other than thegroup consisting of: initial OFDM symbol, the second OFDM symbol, andthe third OFDM symbol, and wherein the subcarriers occupied by theresource elements for carrying the first part of the user-specific pilotsignals are the same as subcarriers occupied by the resource elementsfor carrying the second part of the user-specific pilot signals.
 4. Themethod of claim 1, wherein a second part of the user-specific pilotsignals are carried by resource elements occupying OFDM symbolshorizontally listed in the resource block other than the groupconsisting of: the initial OFDM symbol, the second OFDM symbol, and thethird OFDM symbol, and wherein the sending the user-specific pilotsignals comprises: sending the user-specific pilot signals at a firstantenna port and at a second antenna port, wherein one of the followingconditions is met: any OFDM symbols and subcarriers occupied by theresource elements for carrying the user-specific pilot signals sent atthe first antenna port are different from any OFDM symbols andsubcarriers occupied by the resource elements for carrying theuser-specific pilot signals sent at the second antenna port, and anyOFDM symbols and subcarriers occupied by the resource elements forcarrying the first part of the user-specific pilot signals sent at thefirst antenna port are different from any OFDM symbols and subcarriersoccupied by the resource elements for carrying the first part of theuser-specific pilot signals sent at the second antenna port, and anyOFDM symbols and subcarriers occupied by the resource elements forcarrying the second part of the user-specific pilot signals sent at thefirst antenna port are the same as OFDM symbols and subcarriers occupiedby the resource elements for carrying the second part of theuser-specific pilot signals sent at the second antenna port.
 5. Themethod of claim 1, wherein a second part of the user-specific pilotsignals are carried by resource elements occupying OFDM symbolshorizontally listed in the resource block other than the groupconsisting of: the initial OFDM symbol, the second OFDM symbol, and thethird OFDM symbol, and wherein sending the sub-frame carrying theuser-specific pilot signals comprises: sending the sub-frame carryingthe user-specific pilot signals at a first antenna port and a secondantenna port, wherein locations of the resource elements for carryingthe user-specific pilot signals sent at the first antenna port are thesame as locations of the resource elements for carrying theuser-specific pilot signals sent at the second antenna port; and whereinthe user-specific pilot signals sent at the first antenna port and theuser-specific pilot signals sent at the second antenna port are mappedby using different orthogonal codes.
 6. A method for receiving a pilotsignal, comprising: receiving a resource block carrying user-specificpilot signals; and acquiring the user-specific pilot signals; whereinthe resource block comprises a plurality of resource elements in asymbol subcarrier plane, wherein locations of the resource elements inthe symbol subcarrier plane are determined by Orthogonal FrequencyDivision Multiplexing (OFDM) symbols and subcarriers, wherein a firstpart of the user-specific pilot signals are carried by resource elementsoccupying one or more of the group consisting of: an initial OFDMsymbol, a second OFDM symbol, and a third OFDM symbol, and wherein theinitial OFDM symbol, the second OFDM symbol, and the third OFDM symbolare horizontally listed in the resource block.
 7. The method of claim 6,wherein a second part of the user-specific pilot signals are carried byresource elements occupying OFDM symbols horizontally listed in theresource block other than the group consisting of: the initial OFDMsymbol, the second OFDM symbol, and the third OFDM symbol, and whereinan interval of subcarriers occupied by the resource elements forcarrying the first part of the user-specific pilot signals is the sameas interval of subcarriers occupied by the resource elements forcarrying the second part of the user-specific pilot signals.
 8. Themethod of claim 6, wherein a second part of the user-specific pilotsignals are carried by resource elements occupying OFDM symbolshorizontally listed in the resource block other than the groupconsisting of: the initial OFDM symbol, the second OFDM symbol, and thethird OFDM symbol, and wherein the subcarriers occupied by the resourceelements for carrying the first part of the user-specific pilot signalsare the same as subcarriers occupied by the resource elements forcarrying the second part of the user-specific pilot signals.
 9. Themethod of claim 6, wherein a second part of the user-specific pilotsignals are carried by resource elements occupying OFDM symbolshorizontally listed in the resource block other than the groupconsisting of: the initial OFDM symbol, the second OFDM symbol, and thethird OFDM symbol, and wherein the acquiring the user-specific pilotsignals comprises: receiving the user-specific pilot signals sent at afirst antenna port and a second antenna port; wherein one of thefollowing conditions is met: any OFDM symbols and subcarriers occupiedby the resource elements for carrying the user-specific pilot signalssent at the first antenna port are different from OFDM symbols andsubcarriers occupied by the resource elements for carrying theuser-specific pilot signals sent at the second antenna port, and anyOFDM symbols and subcarriers occupied by the resource elements forcarrying the first part of the user-specific pilot signals sent at thefirst antenna port are different from OFDM symbols and subcarriersoccupied by the resource elements for carrying the first part of theuser-specific pilot signals sent at the second antenna port, and anyOFDM symbols and subcarriers occupied by the resource elements forcarrying the second part of the user-specific pilot signals sent at thefirst antenna port are the same as OFDM symbols and subcarriers occupiedby the resource elements for carrying the second part of theuser-specific pilot signals sent at the second antenna port.
 10. Themethod of claim 6, wherein a second part of the user-specific pilotsignals are carried by resource elements occupying OFDM symbolshorizontally listed in the resource block other than the groupconsisting of: the initial OFDM symbol, the second OFDM symbol, and thethird OFDM symbol, and wherein the acquiring the user-specific pilotsignals comprises: receiving the user-specific pilot signals sent at afirst antenna port and a second antenna port, wherein locations of theresource elements for carrying the user-specific pilot signals sent atthe first antenna port are the same as locations of the resourceelements for carrying the user-specific pilot signals sent at the secondantenna port, and wherein the user-specific pilot signals sent at thefirst antenna port and the user-specific pilot signals sent at thesecond antenna port are mapped by using different orthogonal codes. 11.A device, comprising: a processor configured to generate a resourceblock carrying user-specific pilot signals; and a transmitter configuredto send the user-specific pilot signals, wherein the resource blockcomprises a plurality of resource elements in a symbol-subcarrier plane,wherein locations of the resource elements in the symbol-subcarrierplane are determined by Orthogonal Frequency Division Multiplexing(OFDM) symbols and subcarriers, and wherein a first part of theuser-specific pilot signals are carried by resource elements occupyingat least one of: an initial OFDM symbol, a second OFDM symbol, and athird OFDM symbol horizontally listed in the resource block.
 12. Thedevice of claim 11, wherein a second part of the user-specific pilotsignals are carried by resource elements occupying OFDM symbolshorizontally listed in the resource block other than the groupconsisting of: the initial OFDM symbol, the second OFDM symbol, and thethird OFDM symbol, and wherein an interval of subcarriers occupied bythe resource elements for carrying the first part of the user-specificpilot signals is the same as interval of subcarriers occupied by theresource elements for carrying the second part of the user-specificpilot signals.
 13. The device of claim 11, wherein a second part of theuser-specific pilot signals are carried by resource elements occupyingOFDM symbols horizontally listed in the resource block other than thegroup consisting of: the initial OFDM symbol, the second OFDM symbol,and the third OFDM symbol, and wherein the subcarriers occupied by theresource elements for carrying the first part of the user-specific pilotsignals are the same as subcarriers occupied by the resource elementsfor carrying the second part of the user-specific pilot signals.
 14. Adevice, comprising: a transceiver configured to receive a resource blockcarrying user-specific pilot signals; and a processor configured toacquire the user-specific pilot signals; wherein the resource blockcomprises a plurality of resource elements in a symbol-subcarrier plane,wherein locations of the resource elements in the symbol-subcarrierplane are determined by Orthogonal Frequency Division Multiplexing(OFDM) symbols and subcarriers, and wherein a first part of theuser-specific pilot signals are carried by resource elements occupyingat least one of: an initial OFDM symbol, a second OFDM symbol, and athird OFDM symbol, wherein the initial OFDM symbol, the second OFDMsymbol, and the third OFDM symbol are horizontally listed in theresource block.
 15. The device of claim 14, wherein a second part of theuser-specific pilot signals are carried by resource elements occupyingOFDM symbols horizontally listed in the resource block other than thegroup consisting of: the initial OFDM symbol, the second OFDM symbol,and the third OFDM symbol, and wherein the subcarriers occupied by theresource elements for carrying the first part of the user-specific pilotsignals are the same as subcarriers occupied by the resource elementsfor carrying the second part of the user-specific pilot signals.